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Comment 11 for Public Workshop to Discuss Potential Revisions to GHG Mandatory Reporting Regulation (mrr-2014-ws) - 1st Workshop.
First Name: Milan
Last Name: Steube
Email Address: milans@cox.net
Affiliation:
Subject: Sampling for Flash Liberation Analysis per 95153(v)(1)(A)(1)
Comment:
Clarification is needed regarding the appropriate location to obtain samples of crude oil and produced water to apply the Appendix B flash liberation methodology specified in 95153(v)(1)(A)(1) for calculating emissions from “crude oil, condensate, and produced water sent to storage tanks, ponds, and holding facilities”. As currently written, the method requires sampling from a “primary vessel located in a separator and tank system”. “Primary vessel” is defined in 95102 as "a separator or tank that receives crude oil, condensate, produced water, natural gas, or emulsion from one or more crude oil, condensate, or natural gas wells or field gathering systems”. This seems to leave considerable flexibility in the sampling location. Because the objective is to calculate emissions from “crude oil, condensate, and produced water sent to storage tanks, ponds, and holding facilities”, it seems appropriate to sample such liquids at the vessel immediately upstream of the storage tanks, ponds, or holding facilities. This is because the CO2 and CH4 dissolved in liquid discharged from such a vessel is the CO2 and CH4 potentially liberated from the liquid when it “flashes” in the storage tanks, ponds, and holding facilities. However, ARB staff has recently (verbally) advised samplers and operators that samples must be obtained from the FIRST (i.e., furthest upstream) vessel in a separator and tank system. Sampling at the furthest upstream vessel in a separator and tank system that consists of more than one separation vessel (e.g., a free water knockout followed by a heater treater) is likely to result in overstating emissions from the downstream storage tanks, ponds, and holding facilities. This is because some of the gas entrained in the liquids discharged from the upstream vessel is liberated in downstream vessels that operate at lower pressure and / or higher temperature and, therefore, is no longer dissolved in the liquid conveyed to the storage units. Rather, it is directed elsewhere in the facility (i.e., a fuel gas system, reinjection system, gas processing / sales system, or a flare) via a closed gas collection / conveyance system. This gas only contributes to facility emissions if it is then combusted as fuel gas or in a flare, leaks to atmosphere via equipment components in the gas collection / conveyance system, or is vented to atmosphere via a gas processing / sales system (e.g., an acid gas removal unit that vents CO2 to atmosphere). But the MRR requires these categories of emissions to be separately quantified and reported in accordance with other specified methodologies. So, requiring samples to be obtained at a point further upstream in the system from the vessel immediately upstream of the storage tanks, ponds, and holding facilities would likely result in emissions from the storage tanks, ponds, and holding facilities to be overstated.
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Date and Time Comment Was Submitted: 2014-06-23 21:40:26
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